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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Appraisal of digital terrain elevation data for low-altitude flight

The use of terrain elevation databases in advanced guidance and navigation systems has greatly expanded. However, the limitations and accuracies of these databases must be considered and established prior to safe system flight evaluation. A simple approach to quantify reasonable flight limits is presented and evaluated for a helicopter guidance system dependent on a terrain database. The flight test evaluated involved a helicopter equipped with a Global Positioning System (GPS) receiver and radar altimeter, and a ground station GPS receiver which provided improved helicopter positioning. The precision navigation and radar altimeter data was acquired while flying low-altitude missions in south-central Pennsylvania. The aircraft-determined terrain elevations were compared with the terrain predicted by the Defense Mapping Agency (DMA) Level 1 terrain elevation data for the same area. The results suggest a safe set clearance altitude of 220 ft for flight testing of a DMA-based guidance avionic in the same area.

Zelenka, Richard E.↗
NASA NTRS1992

Linear dynamic analysis of the Space Station Freedom thermal/environmental control system

A methodology for dynamic analysis of the Space Station Freedom thermal/environmental control system is described which uses linear system analysis techniques to determine the ability of the system to accommodate thermal load transients. A nonlinear integrated model of the system as it exists at Stage 6, Man Tended Capability (MTC), is described which encompasses the cabin air cooling system, avionics air cooling system, internal and external thermal control systems. The nonlinear model is linearized at an assumed design operating point, and the linear model is evaluated by comparison with the nonlinear model. Transfer functions are derived to determine the response of the heat rejection system to time-varying thermal loads applied at various points in the heat acquisition system. The frequency response calculated from the transfer functions is used to determine allowable operating envelopes of thermal load magnitude and frequency for each point of application of thermal load. The dynamic operating envelopes provide a quantitative indication of the degree and duration of peak loads which the thermal/environmental system is able to transport and reject.

Tandler, John↗
NASA NTRS1992

Space Shuttle crew compartment debris-contamination

Remedial actions undertaken to reduce debris during manned flights and ground turnaround operations at Kennedy Space Center and Palmdale are addressed. They include redesign of selected ground support equipment and Orbiter hardware to reduce particularization/debris generation; development of new detachable filters for air-cooled avionics boxes; application of tape-on screens to filter debris; and implementation of new Orbiter maintenance and turnaround procedures to clean filters and the crew compartment. Most of these steps were implemented before the return-to-flight of STS-26 in September 1988 which resulted in improved crew compartment habitability and less potential for equipment malfunction.

Goodman, Jerry R.↗
NASA NTRS1992

The General Purpose Work Station, a spacious microgravity workbench

The General Purpose Work Station (GPWS) is a laboratory multiuse facility, as demonstrated during the Spacelab Life Sciences 1 (SLS-1) flight. The unit provided particulate containment under varying conditions, served as an effective work space for manipulating live animals, e.g., rats, served as a containment facility for fixatives, and was proposed for use to conduct in-flight maintenance during connector pin repair. The cabinet has a front door large enough to allow installation of a full-size microscope in-flight and is outfitted with a side window to allow delivery of items into the cabinet without exposure to the spacelab atmosphere. Additional support subsystems include inside cabinet mounting, surgical glove fine manipulations capability, and ac or dc power supply for experiment equipment, as will be demonstrated during Spacelab J. The GPWS, integrated and maintained in a double flight-rack, interfaces to spacelab systems including water cooling, avionics and cabin air, and power. Verification has been completed for multiple spacelab scenarios including SLS-2, SL-J, and SLS-3.

Dalton, Bonnie P.↗
NASA NTRS1992

An assessment of the microgravity and acoustic environments in Space Station Freedom using VAPEPS

The Vibroacoustic Payload Environment Prediction System (VAPEPS) was used to predict the stationary on-orbit environments in one of the Space Station Freedom modules. The model of the module included the outer structure, equipment and payload racks, avionics, and cabin air and duct systems. Acoustic and vibratory outputs of various source classes were derived and input to the model. Initial results of analyses, performed in one-third octave frequency bands from 10 to 10,000 Hz, show that both the microgravity and acoustic environments will be exceeded in some one-third octave bands with the current SSF design. Further analyses indicate that interior acoustic level requirements will be exceeded even if the microgravity requirements are met.

Bergen, Thomas F.↗
NASA NTRS1985

An operational ASDAR system

The story of the Aircraft to Satellite Data Relay (ASDAR) program began when airline meteorologists realized that B-747's and other commercial jets provided cockpit displays of digital values for outside air temperature and winds. Later, when a few B-747's were used to carry portable air quality monitoring equipment for the Global Air Sampling Program (GASP), scientists at NASA-Lewis explored ways in which these digital values could be used to label data collected during the GASP flights. Digital values of GASP analyses were recorded along with digital values of location and altitude, time, winds, and temperature, obtained by microprocessors from within the host aircraft's avionics. These data suggested a way in which manually recorded in-flight meteorological reports could be replaced by an automatic system, which could record winds and air temperatures as often as desired. NASA's prototype ASDAR showed that automated data relay by meteorological geostationary satellites could be accomplished from an aircraft. Testing of the instruments and analyses of its data are examined.

Sparkman, James K., Jr.↗
NASA NTRS1992

Applying reliability models to the maintenance of Space Shuttle software

Software reliability models provide the software manager with a powerful tool for predicting, controlling, and assessing the reliability of software during maintenance. We show how a reliability model can be effectively employed for reliability prediction and the development of maintenance strategies using the Space Shuttle Primary Avionics Software Subsystem as an example.

Schneidewind, Norman F.↗
NASA NTRS1993

STS-55 pad abort: Engine 2011 oxidizer preburner augmented spark igniter check valve leak

The STS-55 initial launch attempt of Columbia (OV102) was terminated on KSC launch pad A March 22, 1993 at 9:51 AM E.S.T. due to violation of an ME-3 (Engine 2011) Launch Commit Criteria (LCC) limit exceedance. The event description and timeline are summarized. Propellant loading was initiated on 22 March, 1993 at 1:15 AM EST. All SSME chill parameters and launch commit criteria (LCC) were nominal. At engine start plus 1.44 seconds, a Failure Identification (FID) was posted against Engine 2011 for exceeding the 50 psia Oxidizer Preburner (OPB) purge pressure redline. The engine was shut down at 1.50 seconds followed by Engines 2034 and 2030. All shut down sequences were nominal and the mission was safely aborted. The OPB purge pressure redline violation and the abort profile/overlay for all three engines are depicted. SSME Avionics hardware and software performed nominally during the incident. A review of vehicle data table (VDT) data and controller software logic revealed no failure indications other than the single FID 013-414, OPB purge pressure redline exceeded. Software logic was executed according to requirements and there was no anomalous controller software operation. Immediately following the abort, a Rocketdyne/NASA failure investigation team was assembled. The team successfully isolated the failure cause to the oxidizer preburner augmented spark igniter purge check valve not being fully closed due to contamination. The source of the contaminant was traced to a cut segment from a rubber O-ring which was used in a fine clean tool during valve production prior to 1992. The valve was apparently contaminated during its fabrication in 1985. The valve had performed acceptably on four previous flights of the engine, and SSME flight history shows 780 combined check valve flights without failure. The failure of an Engine 3 (SSME No. 2011) check valve to close was sensed by onboard engine instruments even though all other engine operations were normal. This resulted in an engine shutdown and safe sequential shutdown of all three engines prior to ignition of the solid boosters.

Source record↗
NASA NTRS1993

Application of new electro-optic technology to Space Station Freedom data management system

A low risk design methodology to permit the local bus structures to support increased data carrying capacities and to speed messages and data flow between nodes or stations on the Space Station Freedom Data Management System in anticipation of growing requirements was evaluated and recommended. The recommended design employs a collateral fiber optic technique that follows a NATO avionic standard that is developed, tested, and available. Application of this process will permit a potential 25 fold increase in data transfer performance on the local wire bus network with a fiber optic network, maintaining the functionality of the low-speed bus and supporting all of the redundant transmission and fault detection capabilities designed into the existing system. The application of wavelength division multiplexing (WDM) technology to both the local data bus and global data bus segments of the Data Management System to support anticipated additional highspeed data transmission requirements was also examined. Techniques were examined to provide a dual wavelength implementation of the fiber optic collateral networks. This dual wavelength implementation would permit each local bus to support two simultaneous high-speed transfers on the same fiber optic bus structure and operate within the limits of the existing protocol standard. A second WDM study examined the use of spectral sliced technology to provide a fourfold increase in the Fiber Distributed Data Interface (FDDI) global bus networks without requiring modifications to the existing installed cable plant. Computer simulations presented indicated that this data rate improvement can be achieved with commercially available optical components.

Husbands, C. R.↗
NASA NTRS1993

Development of a proposed international standard for certification of aircraft to High Intensity Radiated Fields (HIRF)

Avionic systems performing critical functions in modern aircraft are potentially susceptible to the hazards of electromagnetic radiation from ground and airborne transmitters. The Federal Aviation Administration (FAA) requested that the Society of Automotive Engineers (SAE) coordinate the development of procedures and guidance material which can be used during the aircraft certification process to ensure adequate protection against high intensity radiated fields (HIRF). This paper addresses both the technical challenge of drafting a certification procedure and guidance standard as well as the management process used by the SAE subcommittee AE4R to converge a diverse range of opinions by its international membership in the shortest possible time.

Sargent, Noel B.↗
NASA NTRS1993

Power Reactant Storage Assembly (PRSA) (Space Shuttle). PRSA hydrogen and oxygen DVT tank refurbishment

The Power Reactant Storage Assembly (PRSA) liquid hydrogen Development Verification Test (H2 DVT) tank assembly (Beech Aircraft Corporation P/N 15548-0116-1, S/N 07399000SHT0001) and liquid oxygen (O2) DVT tank assembly (Beech Aircraft Corporation P/N 15548-0115-1, S/N 07399000SXT0001) were refurbished by Ball Electro-Optics and Cryogenics Division to provide NASA JSC, Propulsion and Power Division, the capability of performing engineering tests. The refurbishments incorporated the latest flight configuration hardware and avionics changes necessary to make the tanks function like flight articles. This final report summarizes these refurbishment activities. Also included are up-to-date records of the pressure time and cycle histories.

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NASA NTRS1993

Towards the formal verification of the requirements and design of a processor interface unit: HOL listings

This technical report contains the Higher-Order Logic (HOL) listings of the partial verification of the requirements and design for a commercially developed processor interface unit (PIU). The PIU is an interface chip performing memory interface, bus interface, and additional support services for a commercial microprocessor within a fault tolerant computer system. This system, the Fault Tolerant Embedded Processor (FTEP), is targeted towards applications in avionics and space requiring extremely high levels of mission reliability, extended maintenance-free operation, or both. This report contains the actual HOL listings of the PIU verification as it currently exists. Section two of this report contains general-purpose HOL theories and definitions that support the PIU verification. These include arithmetic theories dealing with inequalities and associativity, and a collection of tactics used in the PIU proofs. Section three contains the HOL listings for the completed PIU design verification. Section 4 contains the HOL listings for the partial requirements verification of the P-Port.

Fura, David A.↗
NASA NTRS1993

Towards the formal specification of the requirements and design of a processor interface unit: HOL listings

This technical report contains the HOL listings of the specification of the design and major portions of the requirements for a commercially developed processor interface unit (or PIU). The PIU is an interface chip performing memory interface, bus interface, and additional support services for a commercial microprocessor within a fault-tolerant computer system. This system, the Fault-Tolerant Embedded Processor (FTEP), is targeted towards applications in avionics and space requiring extremely high levels of mission reliability, extended maintenance-free operation, or both. This report contains the actual HOL listings of the PIU specification as it currently exists. Section two of this report contains general-purpose HOL theories that support the PIU specification. These theories include definitions for the hardware components used in the PIU, our implementation of bit words, and our implementation of temporal logic. Section three contains the HOL listings for the PIU design specification. Aside from the PIU internal bus (I-Bus), this specification is complete. Section four contains the HOL listings for a major portion of the PIU requirements specification. Specifically, it contains most of the definition for the PIU behavior associated with memory accesses initiated by the local processor.

Fura, David A.↗
NASA NTRS1993

Evaluation of the efficiency and fault density of software generated by code generators

Flight computers and flight software are used for GN&C (guidance, navigation, and control), engine controllers, and avionics during missions. The software development requires the generation of a considerable amount of code. The engineers who generate the code make mistakes and the generation of a large body of code with high reliability requires considerable time. Computer-aided software engineering (CASE) tools are available which generates code automatically with inputs through graphical interfaces. These tools are referred to as code generators. In theory, code generators could write highly reliable code quickly and inexpensively. The various code generators offer different levels of reliability checking. Some check only the finished product while some allow checking of individual modules and combined sets of modules as well. Considering NASA's requirement for reliability, an in house manually generated code is needed. Furthermore, automatically generated code is reputed to be as efficient as the best manually generated code when executed. In house verification is warranted.

Schreur, Barbara↗
NASA NTRS1993

Towards the formal specification of the requirements and design of a processor interface unit

Work to formally specify the requirements and design of a Processor Interface Unit (PIU), a single-chip subsystem providing memory interface, bus interface, and additional support services for a commercial microprocessor within a fault-tolerant computer system, is described. This system, the Fault-Tolerant Embedded Processor (FTEP), is targeted towards applications in avionics and space requiring extremely high levels of mission reliability, extended maintenance free operation, or both. The approaches that were developed for modeling the PIU requirements and for composition of the PIU subcomponents at high levels of abstraction are described. These approaches were used to specify and verify a nontrivial subset of the PIU behavior. The PIU specification in Higher Order Logic (HOL) is documented in a companion NASA contractor report entitled 'Towards the Formal Specification of the Requirements and Design of a Processor Interfacs Unit - HOL Listings.' The subsequent verification approach and HOL listings are documented in NASA contractor report entitled 'Towards the Formal Verification of the Requirements and Design of a Processor Interface Unit' and NASA contractor report entitled 'Towards the Formal Verification of the Requirements and Design of a Processor Interface Unit - HOL Listings.'

Fura, David A.↗
NASA NTRS1993

Lunar transportation system

The University Space Research Association (USRA) requested the University of Minnesota Spacecraft Design Team to design a lunar transportation infrastructure. This task was a year long design effort culminating in a complete conceptual design and presentation at Johnson Space Center. The mission objective of the design group was to design a system of vehicles to bring a habitation module, cargo, and crew to the lunar surface from LEO and return either or both crew and cargo safely to LEO while emphasizing component commonality, reusability, and cost effectiveness. During the course of the design, the lunar transportation system (LTS) has taken on many forms. The final design of the system is composed of two vehicles, a lunar transfer vehicle (LTV) and a lunar excursion vehicle (LEV). The LTV serves as an efficient orbital transfer vehicle between the earth and the moon while the LEV carries crew and cargo to the lunar surface. Presented in the report are the mission analysis, systems layout, orbital mechanics, propulsion systems, structural and thermal analysis, and crew systems, avionics, and power systems for this lunar transportation concept.

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NASA NTRS1992

Design project: Viper

The design specification of the primary flight trainer are: must conform to F.A.R. 23, including the crashworthiness standards; is limited to two to four occupants; engine must be FAA certified; must comply with FAA standards for VFR and allow for upgrade to IFR flights; must be at least utility category with good spin recovery characteristics; must have a structural lifetime of at least 10,000 flight hours; capable of either of two training missions: climb to 5,000 ft., cruise 500 Nm. plus reserve, land, or climb to 1,000 ft. and descend ten cycles for landing practice, climb to 3,000 ft., maneuver at two g's for 15 minutes, cruise 100 Nm. and land; must have a cruise speed of at least 120 knots; must take-off or land on a runway no longer than 3,000 ft; and has a cost goal of $50,000, not including avionics, for production of 1,000 airplanes over a five year period.

Haithcock, Stephen↗
NASA NTRS1993

STS-51 pad abort. OV103-engine 2033 (ME-2) fuel flowmeter sensor open circuit

The STS-51 initial launch attempt of Discovery (OV-103) was terminated on KSC launch pad 39B on 12 Aug. 1993 at 9:12 AM E.S.T. due to a sensor redundancy failure in the liquid hydrogen system of ME-2 (Engine 2033). The event description and time line are summarized. Propellant loading was initiated on 12 Aug. 1993 at 12:00 AM EST. All space shuttle main engine (SSME) chill parameters and Launch Commit Criteria (LCC) were nominal. At engine start plus 1.34 seconds a Failure Identification (FID) was posted against Engine 2033 for exceeding the 1800 spin intra-channel (A1-A2) Fuel Flowrate sensor channel qualification limit. The engine was shut down at 1.50 seconds followed by Engines 2032 and 2030. All shut down sequences were nominal and the mission was safely aborted. SSME Avionics hardware and software performed nominally during the incident. A review of vehicle data table (VDT) data and controller software logic revealed no failure indications other than the single FID 111-101, Fuel Flowrate Intra-Channel Test Channel A disqualification. Software logic was executed according to requirements and there was no anomalous controller software operation. Immediately following the abort, a Rocketdyne/NASA failure investigation team was assembled. The team successfully isolated the failure cause to an open circuit in a Fuel Flowrate Sensor. This type of failure has occurred eight previous times in ground testing. The sensor had performed acceptably on three previous flights of the engine and SSME flight history shows 684 combined fuel flow rate sensor channel flights without failure. The disqualification of an Engine 2 (SSME No. 2033) Fuel Flowrate sensor channel was a result of an instrumentation failure and not engine performance. All other engine operations were nominal. This disqualification resulted in an engine shutdown and safe sequential shutdown of all three engines prior to ignition of the solid boosters.

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